WASHINGTON (Reuters) - The United States is preparing to impose “very significant” Venezuela-related sanctions against financial institutions in the coming days, U.S. special envoy Elliott Abrams said on Tuesday.

Abrams did not elaborate on the fresh measures but his warning came a day after the U.S. Treasury imposed sanctions on Russian bank Evrofinance Mosnarbank for helping Venezuelan state oil firm PDVSA evade U.S. financial restrictions.

Abrams said Washington was also preparing to withdraw more U.S. visas from Venezuelans with close ties to President Nicolas Maduro.

Washington has taken the lead in recognizing opposition leader Juan Guaido as Venezuela’s rightful president after the 35-year-old Congress chief declared Maduro’s 2018 re-election a fraud and announced an interim presidency in January. Most countries in Europe and Latin America have followed suit.

Abrams’ comments came as Venezuela ordered American diplomats to leave the country within 72 hours.

Washington said it had decided to withdraw the remaining diplomats due to deteriorating conditions in Venezuela, which has been plunged into its worst blackout on record.

Abrams emphasized that the withdrawal of diplomats was not a change in U.S. policy.

“This does not represent any change in U.S. policy toward Venezuela, nor does it represent any reduction in the commitment we have to the people of Venezuela and to their struggle for democracy,” he said, adding that the U.S. intended to keep up pressure on Maduro through sanctions.

“You will see very soon a significant number of additional visa revocations. You will see in the coming days some very significant additional sanctions,” Abrams added.

He said the United States was in talks with other countries that could act as its “protecting power” in Venezuela to ensure the safety of the U.S. embassy’s premises and provide assistance to Americans in trouble.

A “protecting power” is a country that represents another in cases where two countries have broken off diplomatic relations. Washington, for example, has appointed Switzerland as its “protecting power” in Iran.

“We are trying to decide on a protecting power,” Abrams said.

He said the safety of U.S. diplomats was a key factor in the withdrawal decision reached by U.S. Secretary of State Mike Pompeo in the late hours of Monday night.

Reporting by Lesley Wroughton and David Alexander; writing by Doina Chiacu; editing by Bill Trott